STUDY OF THE EFFECT OF THE WEATHER VARIATION ON THE OCEAN ENVIRONMENT

通过实验和计算研究了天气变化引起的海洋表层混合过程，以阐明其对封闭海域水质的影响。首先，我们选择二维空腔流来重现均匀风持续吹过海洋表面稳定分层流体时的混合过程。结果表明，在顶部的下游角落形成了一个初级循环，逐渐增长，但被层状流体包围，就像一堵墙一样。研究发现，由于基本密度梯度的侵蚀而形成的密度界面受到初级环流的扭曲。这是下层流体混合的重要机制之一。其次，通过计算和实验模拟了大气对海洋表层降温的混合过程，并考察了温度变化对混合过程的影响。结果表明，水平平均密度的垂向剖面图将分层发育的混合层与下层区分开来。当冷却开始时，在靠近冷却顶面的薄层中形成三维规则的胞体结构。冷而致密的液体汇聚到细胞壁中，并沿着细胞壁下降。研究发现，三维垂直对流的流型依赖于雷诺数，并可能影响表面冷却的混合速率。我们已经建立了这一主题研究的基石，因为我们对上层海洋混合过程的主要特征的理解足以预测辐射、温度和风应力等天气条件对这一过程的影响，尽管它们仅限于简单的条件。

We investigate the mixing process in the surface layer of the ocean caused by the weather change by the experiment and the computation to elucidate its effect on the water quality in the closed sea.First, we choose the two-dimensional cavity flow to reproduce the mixing process when the uniform wind continues to blow over the stably stratified fluid in the ocean surface. The results show that a primary circulation forms in the top downstream corner, growing gradually, but bounded by a stratified fluid beneath as it were a wall. It is found that the density interface formed by erosion of the basic density gradient is distorted by the primary circulation. This is one of the important mechanisms for the mixing of the fluid in the lower layer beneath.Next, we simulate the mixing process in the upper ocean by cooling the surface by the atmosphere by the computation and experiment, and we examine the effects of the temperature variation on the process. The results show that the vertical profile of the horizontally averaged density distinguishes the mixed layer developing from the lower layer of stratification. When the cooling starts, the three-dimensional and regular cell structure is formed in the thin layer adjacent to the cooling top surface. The cool and dense fluid converges into the cell wall and falls down along it. It is found that the flow pattern of the three-dimensional vertical convection is dependent on the Reynolds number and it may affect the rate of mixing by surface cooling.We have established the comer stone of the study on this theme because our understanding of the dominant feature of this process of the mixing in the upper ocean is good enough to predict the effects on the process of the weather conditions such as radiation, temperature, and wind stress although they are limited to the simple conditions.